Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes a substrate, a transistor and a heat dissipation structure. The substrate includes first and second semiconductor layers, and includes an insulating layer disposed between the first and second semiconductor layers. The substrate has a recess extending into the insulating layer from a surface of the first semiconductor layer. The transistor includes a hetero-junction structure, a gate electrode, a drain electrode and a source electrode. The hetero-junction structure is disposed on the second semiconductor layer. The gate, drain and source electrodes are disposed over the hetero-junction structure. The gate electrode is located between the drain electrode and the source electrode, and an active area of the hetero-junction structure located between the drain electrode and the source electrode is overlapped with the recess of the substrate. The heat dissipation structure is disposed on the surface of the first semiconductor layer, and extends into the recess.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 108108136, filed on Mar. 12, 2019. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND Technical Field

The present disclosure is related to a semiconductor device and amanufacturing method thereof, and particularly, to a semiconductordevice having a heat dissipation structure and a manufacturing methodthereof.

Description of Related Art

Compound semiconductor (e.g., group III-V semiconductor) has advantagessuch as large bandgap and high carrier mobility, thus the semiconductordevice formed of compound semiconductor can be a great candidate forbeing used in high frequency communication and high power applications.However, problem of heat dissipation usually comes with operation athigh frequency and high power. Therefore, improving heat dissipationability of such semiconductor device is important in the art.

SUMMARY

Accordingly, a semiconductor device with an improved heat dissipationability and a manufacturing method of this semiconductor device areprovided.

In an aspect of the present disclosure, a semiconductor device isprovided. The semiconductor device comprises: a substrate, comprising afirst semiconductor layer, a second semiconductor layer and aninsulating layer disposed between the first semiconductor layer and thesecond semiconductor layer, wherein the substrate has a recess, and therecess extends into the insulating layer from a surface of the firstsemiconductor layer; a transistor, comprising a hetero-junctionstructure, a gate electrode, a drain electrode and a source electrode,wherein the hetero-junction structure is disposed on the secondsemiconductor layer, the gate electrode, the drain electrode and thesource electrode are disposed on the hetero-junction structure, the gateelectrode is located between the drain electrode and the sourceelectrode, and an active area of the hetero-junction structure betweenthe drain electrode and the source electrode is overlapped with therecess of the substrate; and a heat dissipation structure, disposed onthe surface of the first semiconductor layer, and extending into therecess.

In some embodiments, the recess is further overlapped with the drainelectrode and the source electrode.

In some embodiments, an area of an orthogonal projection of the recesson the second semiconductor layer is greater than or equal to an area ofan orthogonal projection of the hetero-junction structure on the secondsemiconductor layer.

In some embodiments, the heat dissipation structure comprises aplurality of multilayer structures stacking on one another, eachmultilayer structure comprises an adhesive layer and a heat dissipationlayer, and the adhesive layer is closer to the substrate than the heatdissipation layer in the same multilayer structure.

In some embodiments, a ratio of a thickness of the heat dissipationlayer with respect to a thickness of the adhesive layer ranges from 3:1to 4:1.

In some embodiments, an amount of the multilayer structures ranges from4 to 6.

In some embodiments, the hetero-junction structure comprises a channellayer, a spacer layer and a barrier layer, wherein the channel layer isdisposed between the second semiconductor layer of the substrate and thebarrier layer, and the spacer layer is located between the channel layerand the barrier layer.

In some embodiments, a portion of the insulating layer overlapped with abottom surface of the recess has a first thickness, another portion ofthe insulating layer not overlapped with the recess has a secondthickness, and a ratio of the first thickness with respect to the secondthickness ranges from 0.4 to 0.6.

In some embodiments, the semiconductor device further comprises a bufferlayer. The buffer layer is disposed between the second semiconductorlayer of the substrate and the transistor.

In another aspect of the present disclosure, a manufacturing method of asemiconductor device is provided. The manufacturing method of thesemiconductor device comprises: providing a substrate, wherein thesubstrate comprises a first semiconductor layer, a second semiconductorlayer and an insulating layer disposed between the first semiconductorlayer and the second semiconductor layer; forming a transistor on thesecond semiconductor layer of the substrate, wherein the transistorcomprises a hetero-junction structure and a gate electrode, a drainelectrode and a source electrode disposed on the hetero-junctionstructure, and the gate electrode is located between the drain electrodeand the source electrode; forming a recess at a surface of thesubstrate, wherein the recess extends into the insulating layer from abottom surface of the first semiconductor layer; and forming a heatdissipation structure on the surface of the substrate, wherein the heatdissipation structure extends into the recess.

In some embodiments, the manufacturing method of the semiconductordevice further comprises: thinning the first semiconductor layer beforeforming the recess.

As above, the semiconductor device according to embodiments of thepresent disclosure includes a transistor formed at a front side of asubstrate, and further includes a heat dissipation structure disposed ata back side of a substrate. By disposing the heat dissipation structure,thermal energy generated by the transistor can be dissipated through thesubstrate and the heat dissipation structure. The substrate may be asemiconductor-on-insulator (SOI) substrate, and the back side of thesubstrate has a recess. The recess is overlapped with the active area ofthe transistor, and extends into the insulating layer of the substratefrom the back side of the substrate. In this way, the heat dissipationstructure may extend into the recess, and is in contact with theinsulating layer. Therefore, thermal energy accumulated in theinsulating layer that has a relatively low thermal conductivity can beeffectively dissipated through the heat dissipation structure. As aresult of improvement of heat dissipation ability, reliability of thesemiconductor device can be improved. On the other hand, a portion ofthe substrate outside the recess may have a relatively large thickness,so as to provide sufficient mechanical strength to the semiconductordevice.

To make the aforementioned more comprehensible, several embodimentsaccompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate exemplaryembodiments of the disclosure and, together with the description, serveto explain the principles of the disclosure.

FIG. 1 is a process flow diagram illustrating a manufacturing method ofa semiconductor device according to some embodiments of the presentdisclosure.

FIG. 2A through FIG. 2G are schematic cross-sectional views illustratingstructures at various stages during the manufacturing method of thesemiconductor device as shown in FIG. 1.

FIG. 3 is a schematic cross-sectional view illustrating a semiconductordevice according to other embodiments of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a process flow diagram illustrating a manufacturing method ofa semiconductor device 10 according to some embodiments of the presentdisclosure. FIG. 2A through FIG. 2G are schematic cross-sectional viewsillustrating structures at various stages during the manufacturingmethod of the semiconductor device 10 as shown in FIG. 1.

Referring to FIG. 1 and FIG. 2A, step S100 is performed, and a substrate100 is provided. In some embodiments, the substrate 100 may be asemiconductor-on-insulator (SOI) wafer. In these embodiments, thesubstrate 100 may include a first semiconductor layer 102, a secondsemiconductor layer 104 and an insulating layer 106 disposed between thefirst semiconductor layer 102 and the second semiconductor layer 104.The first semiconductor layer 102 and the second semiconductor layer 104are respectively made of a semiconductor material, whereas theinsulating layer 106 is made of an insulating material. For instance,the semiconductor material may be silicon, and the insulating materialmay be silicon oxide. In some embodiments, the first semiconductor layer102 has a thickness greater than a thickness of the second semiconductorlayer 104. In these embodiments, the thickness of the firstsemiconductor layer 102 may range from 600 μm to 625 μm, and thethickness of the second semiconductor layer 104 may range from 5 μm to10 μm. On the other hand, a thickness of the insulating layer 106 mayrange from 0.5 μm to 1 μm.

In some embodiments, step S102 is performed, and a buffer layer 108 isformed on the second semiconductor layer 104 of the substrate 100. Insome embodiments, substantially the entire second semiconductor layer104 of the substrate 100 is covered by the buffer layer 108. In someembodiments, a material of the buffer layer 108 may include a nitride ofa group III element or a group III-V compound semiconductor. Forinstance, the material of the buffer layer 108 may include InAlGaN,AlGaN, AlInN, InGaN, AlN, GaN or combinations thereof. A method forforming the buffer layer 108 may include an epitaxial process. In someembodiments, a thickness of the buffer layer 108 ranges from 1.2 μm to 2μm. By disposing the buffer layer 108, stress induced by latticeconstant mismatch and/or coefficient of thermal expansion (CTE)difference between the substrate 100 and the subsequently formed layers(e.g., the channel layer 110 or the spacer layer 111).

Step S104 is performed, and a channel layer 110 and a barrier layer 112are sequentially formed on the second semiconductor layer 104 of thesubstrate 100. In other words, the channel layer 110 may be locatedbetween the barrier layer 112 and the second semiconductor layer 104 ofthe substrate 100. In those embodiments where the buffer layer 108 isformed on the second semiconductor layer 104 of the substrate 100, thechannel layer 110 may be located between the buffer layer 108 and thebarrier layer 112. Materials of the channel layer 110 and the barrierlayer 112 may respectively include a nitride of a group III element or agroup III-V compound semiconductor, and are different from each other.For instance, the material of the channel layer 110 may be GaN, whereasthe material of the barrier layer 112 may be InAlN, AlGaN, InAlGaN, thelike or combinations thereof. In addition, a thickness of the channellayer 110 may range from 200 nm to 300 nm, whereas a thickness of thebarrier layer 112 may range from 15 nm to 20 nm. In some embodiments,the channel layer 110 and the barrier layer 112 may be formed byepitaxial processes. Moreover, in some embodiments, a spacer layer 111may be disposed between the channel layer 110 and the barrier layer 112.A material of the spacer layer 111 may include AlN. A thickness of thespacer layer 111 may range from 0.5 nm to 2 nm. In addition, the spacerlayer 111 may also be formed by an epitaxial process.

Referring to FIG. 1 and FIG. 2B, step S106 is performed, and the channellayer 110 and the barrier layer 112 are patterned. In this way, ahetero-junction structure 114 including the patterned channel layer 110and barrier layer 112 is formed. In those embodiments where the spacerlayer 111 is disposed between the channel layer 110 and the barrierlayer 112, the spacer layer 111 may be patterned along with the channellayer 110 and the barrier layer 112 during the step S106. In theseembodiments, the hetero-junction structure 114 may further include thepatterned spacer layer 111. A method for patterning the channel layer110, the spacer layer 111 and the barrier layer 112 may include alithography process and an etching process. In addition, the bufferlayer 108 may be functioned as an etching stop layer during the etchingprocess. Even though only a single hetero-junction structure 114 isdepicted in FIG. 2B, multiple hetero-junction structures 114 may beactually formed on the substrate 100, and these hetero-junctionstructures 114 may be laterally separated from one another. Thoseskilled in the art may adjust dimensions of each hetero-junctionstructure 114 and spacing between adjacent hetero-junction structures114 according to design requirements, the present disclosure is notlimited thereto.

Referring to FIG. 1 and FIG. 2C, step S108 is subsequently performed,and a gate electrode GE, a drain electrode DE and a source electrode SEare formed on the hetero-junction structure 114. In some embodiments, amethod for forming the gate electrode GE, the drain electrode DE and thesource electrode SE includes forming an insulating pattern 116 havingmultiple openings on a top surface of the barrier layer 112, and thenfilling a conductive material into these openings, to form the gateelectrode GE, the drain electrode DE and the source electrode SE. Theinsulating pattern 116 is made of an insulating material (e.g., siliconoxide). A material of the gate electrode GE may include metal or metalnitride (e.g., Ta, TaN, Ti, TiN, W, Pd, Ni, Au, Al or combinationsthereof), metal silicide (e.g., WSi_(x)) or other suitable material thatcould form schottky contact with the barrier layer 112. In addition,materials of the drain electrode DE and the source electrode SE mayrespectively include Ti, Al, Ni, Au, or other material that could formohmic contact with the barrier layer 112. In some embodiments, athickness of the gate electrode GE may range from 150 nm to 200 nm,whereas the drain electrode DE and the source electrode SE mayrespectively have a thickness ranging from 330 nm to 350 nm. A methodfor forming the gate electrode GE, the drain electrode DE and the sourceelectrode SE may include a chemical vapor deposition (CVD) process, aphysical vapor deposition (PVD) process (e.g., a sputtering process) ora combination thereof.

Referring to FIG. 1 and FIG. 2C, in some embodiments, step S110 isperformed, and a protection pattern 118, a conductive pad 120 and aconductive pad 122 are formed on the hetero-junction structure 114. Abody portion of the protection patter 118 partially covers top surfacesof the gate electrode GE, the drain electrode DE and the sourceelectrode SE, and may cover a top surface of the insulating pattern 116.In addition, the protection pattern 118 may have openings exposing thedrain electrode DE and the source electrode SE. Although not depicted inFIG. 2C, the protection pattern 118 may further have an opening exposingthe gate electrode GE. In some embodiments, the protection pattern 118further extends onto sidewalls of the drain electrode DE, the sourceelectrode SE and the hetero-junction structure 114. In some embodiments,a material of the protection pattern 118 may include silicon oxide,silicon nitride, other insulating material or combinations thereof. Onthe other hand, the conductive pad 120 and the conductive pad 122partially cover the protection pattern 118, and extend into the openingsexposing the drain electrode DE and the source electrode SE,respectively. The conducive pad 120 and the conductive pad 122 arerespectively formed of a conductive material, such as Ti, Au, the likeor combinations thereof. In this way, the conductive pad 120 and theconductive pad 122 could be electrically connected to the drainelectrode DE and the source electrode SE, respectively. In someembodiments, the conductive pad 120 and the conductive pad 122 extend toa sidewall of the hetero-junction 114 along a surface of the protectionpattern 118, and may further extend onto portions of the substrate 100(or the buffer layer 108) at opposite sides of the hetero-junctionstructure 114.

Up to here, a transistor T has been formed on the substrate 100 (or thebuffer layer 108). The transistor T may be a high electron mobilitytransistor (HEMT). The hetero-junction structure 114 of the transistor Tincludes at least two different compound semiconductors, andtwo-dimensional electron gas or two-dimensional hole gas may be inducedat the hetero-junction structure 114 by spontaneous polarization effectand piezoelectric polarization effect. This two-dimensional electron gasor two-dimensional hole gas may be functioned as a conductive channel ofthe transistor T. Whether the conductive channel is cut off can becontrolled by the gate electrode GE of the transistor T. When theconductive channel continuously extends in the hetero-junction structure114, electrical current flows through an active area AA of thehetero-junction structure 114 between the drain electrode DE and thesource electrode SE, and the transistor T is in an on-state. On theother hand, when the conductive channel is cut off, the transistor T isin an off-state.

In some embodiments, an interconnection structure (not shown) may befurther formed on the transistor T. The interconnection structure may beconfigured to interconnect different transistors T. In addition, signalscan be provided to or output from the transistor T through theinterconnection structure.

Referring to FIG. 1 and FIG. 2D, in some embodiments, step S112 isperformed, such that the substrate 100 is flipped over, and thestructure formed over the second semiconductor layer 104 of thesubstrate 100 is attached onto a carrier CA. In some embodiments, thestructure shown in FIG. 2C is flipped over, and attached to the carrierCA from above the carrier CA. As such, the first semiconductor layer 102of the substrate 100 faces upwardly, whereas the transistor T and theinterconnection structure (not shown) face toward the carrier CA. Inaddition, in some embodiments, an adhesive layer (not shown) may bepreliminarily formed on a surface of the carrier CA. In this way, thestructure formed on the second semiconductor layer 104 of the substrate100 may be attached to the carrier CA through the adhesive layer. Forinstance, the adhesive layer may be a light-to-heat-conversion (LTHC)release layer.

Referring to FIG. 1 and FIG. 2E, step S114 is performed, and the firstsemiconductor layer 102 of the substrate 100 is thinned. For instance, aportion 102 a of the first semiconductor layer 102 is removed from asurface of the first semiconductor layer 102 facing away from the secondsemiconductor layer 104 by a mechanical polishing process, so as toperform thinning on the first semiconductor layer 102. In someembodiments, a ratio of a thickness of the remained first semiconductorlayer 102 with respect to a thickness of the un-thinned firstsemiconductor layer 102 ranges from 1:5 to 1:6.

Referring to FIG. 1 and FIG. 2F, step S116 is performed, and a recess RSis formed at a surface of the substrate 100 facing away from thetransistor T. The recess RS extend into the substrate 100 from a surfaceof the first semiconductor layer 102. In addition, the recess RS isoverlapped with the active area AA of the hetero-junction structure 114located between the drain electrode DE and the source electrode SE. Inthis way, thermal energy generated by the transistor T can be dissipatedthrough the heat dissipation structure 124 subsequently formed in therecess RS of the substrate 100. Particularly, thermal energy generatedfrom the active area AA of the transistor T can be effectivelydissipated through the heat dissipation structure 124. On the otherhand, portions of the substrate 100 outside the recess RS still have arelatively large thickness, so as to provide sufficient mechanicalstrength. In some embodiments, the recess RS is further overlapped withthe drain electrode DE and the source electrode SE. In theseembodiments, an area of an orthogonal projection of the recess RS on thesecond semiconductor layer 104 may be greater than or equal to an areaof an orthogonal projection of the hetero-junction structure 114 on thesemiconductor layer 104. In some embodiments, an area of the recess RSmay range from 10⁴ μm² to 2.25×10⁴ μm². In addition, a ratio of a depthof the recess RS with respect to a thickness of the thinned substrate100 may be less than 1, and greater than or equal to 0.67. A method forforming the recess RS includes a lithography process and an etchingprocess. In some embodiments, a photoresist pattern (not shown) may beformed on the first semiconductor layer 102. The photoresist pattern hasan opening for defining location of the recess RS. Subsequently, anetching process may be performed on the first semiconductor layer 102 byusing the photoresist pattern as a shadow mask, so as to form the recessRS. Thereafter, the photoresist pattern may be removed.

In some embodiments, the recess RS extends into the insulating layer106, which is less thermally conductive than the first and secondsemiconductor layers 102, 104, from the surface of the firstsemiconductor layer 102. In this way, thermal energy accumulated in thesubstrate 100 can be more effectively dissipated through the heatdissipation structure 124 subsequently formed in the recess RS. In theseembodiments, a method for forming the recess RS further includesremoving a portion of the insulating layer 106. As such, an exposed topsurface of the insulating layer 106 may define a bottom surface of therecess RS, and exposed sidewalls of the insulating layer 106 and thefirst semiconductor layer 102 may collectively define a sidewall of therecess RS. A portion of the insulating layer 106 overlapped with thebottom surface of the recess RS has a thickness T1, wherein anotherportion of the insulating layer 106 not overlapped with the recess RShas a thickness T2. In some embodiments, a ratio of the thickness T1with respect to the thickness T2 ranges from 0.4 to 0.6.

Referring to FIG. 1 and FIG. 2G, step S118 is performed, and a heatdissipation structure 124 is formed on a surface of the substrate 100facing away from the transistor T. Thereafter, the carrier CA may beremoved, and the current structure may be flipped over, so as to formthe structure shown in FIG. 2G. The heat dissipation structure 124extends into the recess RS from above the surface of the firstsemiconductor layer 102. In those embodiments where the recess RSextends into the insulating layer 106, the heat dissipation structure124 may be in contact with the insulating layer 106. In someembodiments, the heat dissipation structure 124 includes a plurality ofmultilayer structures 126 stacking over one another. Each multilayerstructure 126 may include an adhesive layer 128 and a heat dissipationlayer 130. In each multilayer structure 126, the adhesive layer 128 iscloser to the substrate 100 than the heat dissipation layer 130. Inother words, the adhesive layers 128 and the heat dissipation layers 130may be alternately arranged along a direction away from the substrate100. By disposing the adhesive layers 128, adhesion between the heatdissipation layers 130 and the substrate 100 as well as adhesion betweenheat dissipation layers 130 can be improved. In some embodiments, theadhesive layers 128 are made of a metal material. In these embodiments,the adhesive layers 128 are not only beneficial to adhesion, but alsoadvantageous to heat dissipation. For instance, the material of theadhesive layers 128 may include Ti. Moreover, the heat dissipationlayers 130 may be made of a material having high thermal conductivity(such as greater than 600 W/mK). For instance, the heat dissipationlayers 130 may be made of diamond-like carbon (DLC) films. In someembodiments, the heat dissipation structure 124 includes 4 to 6multilayer structures 126. In each multilayer structure 126, a ratio ofa thickness of the heat dissipation layer 130 with respect to athickness of the adhesive layer 128 may range from 3:1 to 4:1. Forinstance, the thickness of the heat dissipation layer 130 may range from1500 nm to 2000 nm, whereas the thickness of the adhesive layer 128 mayrange from 500 nm to 600 nm.

In some embodiments, the heat dissipation structure 124 is conformallyformed on the surface of the substrate 100. In this way, a surface ofthe heat dissipation 124 may have a recess RS1 in corresponding to therecess RS of the substrate 100. A depth of the recess RS1 may be lessthan the depth of the recess RS. In addition, the depth of the recessRS1 may be decreased as an amount of the multilayer structures 126increases. In alternative embodiments, the heat dissipation structure124 has a substantially flat surface, which is free of a recess. Inthese alternative embodiments, the amount of the multilayer structures126 in the heat dissipation structure 124 may be greater than 5.

Up to here, the semiconductor device 10 has been formed. Thesemiconductor device 10 includes the transistor T formed at a front sideof the substrate 100, and further includes the heat dissipationstructure 124 disposed at a back side of the substrate 100. By disposingthe heat dissipation structure 124, the thermal energy generated by thetransistor T can be dissipated through the substrate 100 and the heatdissipation structure 124. The substrate 100 may be a SOI substrate, andthe back side of the substrate 100 has the recess RS. The recess RS isoverlapped with the active area AA of the transistor T, and extends intothe insulating layer 106 of the substrate 100 from the back side of thesubstrate 100. In this way, the heat dissipation structure 124 mayextend into the recess RS, and is in contact with the insulating layer106. Therefore, thermal energy accumulated in the insulating layer 106that has a relatively low thermal conductivity can be effectivelydissipated through the heat dissipation structure 124. As a result ofimprovement of heat dissipation ability, reliability of thesemiconductor device 10 can be improved. On the other hand, the portionof the substrate 100 outside the recess RS may have a relatively largethickness, so as to provide sufficient mechanical strength to thesemiconductor device 10.

FIG. 3 is a schematic cross-sectional view illustrating a semiconductordevice 10 a according to other embodiments of the present disclosure.

Referring to FIG. 2G and FIG. 3, the semiconductor device 10 a shown inFIG. 3 is similar to the semiconductor device 10 as shown in FIG. 2G.Only the difference therebetween will be described, the same or the likeparts would not be repeated again. In addition, the same or the likelabels are referred to the same or the like components (e.g., the recessRS′ as shown in FIG. 3 and the recess RS as shown in FIG. 2G). Referringto FIG. 3, an area of an orthogonal projection of the recess RS′ on thesecond semiconductor layer 104 is smaller than an area of an orthogonalprojection of the hetero-junction structure 114 on the secondsemiconductor layer 104. As such, the hetero-junction structure 114 isnot entirely overlapped with the recess RS′. In some embodiments,substantially the entire active area AA of the hetero-junction structure114 is overlapped with the recess RS′, whereas other area of thehetero-junction structure 114 is not entirely overlapped with the recessRS′. In these embodiments, the drain electrode DE and the sourceelectrode SE of the transistor T are partially overlapped with therecess RS′, rather than entirely overlapped with the recess RS′.

Since the recess RS′ at the back side of the substrate 100 is stilloverlapped with the active area AA of the transistor T and extendinginto the insulating layer 106, thus thermal energy generated by thetransistor T can still be effectively dissipated through the substrate100 and the heat dissipation structure 124 formed at the back side ofthe substrate 100. Moreover, since the recess RS′ of the substrate 100has a relatively small area, a mechanical strength of the substrate 100can be improved. Furthermore, the recess RS1′ in corresponding to therecess RS′ could have a relatively small area.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed embodimentswithout departing from the scope or spirit of the disclosure. In view ofthe foregoing, it is intended that the disclosure covers modificationsand variations provided that they fall within the scope of the followingclaims and their equivalents.

What is claimed is:
 1. A semiconductor device, comprising: a substrate,comprising a first semiconductor layer, a second semiconductor layer andan insulating layer disposed between the first semiconductor layer andthe second semiconductor layer, wherein the substrate has a recess, andthe recess extends into the insulating layer from a surface of the firstsemiconductor layer, a recessed surface of the insulating layer definesa top surface of the recess, and a recessed portion of the insulatinglayer has a first thickness less than a second thickness of portions ofthe insulating layer aside the recess; a transistor, comprising ahetero-junction structure, a gate electrode, a drain electrode and asource electrode, wherein the hetero-junction structure is disposed onthe second semiconductor layer, the gate electrode, the drain electrodeand the source electrode are disposed on the hetero-junction structure,the gate electrode is located between the drain electrode and the sourceelectrode, and an active area of the hetero-junction structure betweenthe drain electrode and the source electrode is overlapped with therecess of the substrate; and a heat dissipation structure, disposed onthe surface of the first semiconductor layer, and extending into therecess.
 2. The semiconductor device according to claim 1, wherein therecess is further overlapped with the drain electrode and the sourceelectrode.
 3. The semiconductor device according to claim 2, wherein anarea of an orthogonal projection of the recess on the secondsemiconductor layer is greater than or equal to an area of an orthogonalprojection of the hetero-junction structure on the second semiconductorlayer.
 4. The semiconductor device according to claim 1, wherein theheat dissipation structure comprises a plurality of multilayerstructures stacking on one another, each multilayer structure comprisesan adhesive layer and a heat dissipation layer, and the adhesive layeris closer to the substrate than the heat dissipation layer in the samemultilayer structure.
 5. The semiconductor device according to claim 4,wherein a ratio of a thickness of the heat dissipation layer withrespect to a thickness of the adhesive layer ranges from 3:1 to 4:1. 6.The semiconductor device according to claim 4, wherein an amount of themultilayer structures ranges from 4 to
 6. 7. The semiconductor deviceaccording to claim 1, wherein the hetero-junction structure comprises achannel layer, a spacer layer and a bather layer, wherein the channellayer is disposed between the second semiconductor layer of thesubstrate and the barrier layer, and the spacer layer s located betweenthe channel layer and the barrier layer.
 8. The semiconductor deviceaccording to claim 1, wherein a ratio of the first thickness withrespect to the second thickness ranges from 0.4 to 0.6.
 9. Amanufacturing method of a semiconductor device, comprising: providing asubstrate, wherein the substrate comprises a first semiconductor layer,a second semiconductor layer and an insulating layer disposed betweenthe first semiconductor layer and the second semiconductor layer;forming a transistor on the second semiconductor layer of the substrate,wherein the transistor comprises a hetero-junction structure and a gateelectrode, a drain electrode and a source electrode disposed on thehetero-junction structure, and the gate electrode is located between thedrain electrode and the source electrode; forming a recess at a surfaceof the substrate, wherein the recess extends into the insulating layerfrom a bottom surface of the first semiconductor layer, a recessedsurface of the insulating layer defines a top surface of the recess, anda recessed portion of the insulating layer has a first thickness lessthan a second thickness of portions of the insulating layer aside therecess; and forming a heat dissipation structure on the surface of thesubstrate, wherein the heat dissipation structure extends into therecess.
 10. The manufacturing method of the semiconductor deviceaccording to claim 9, further comprising thinning the firstsemiconductor layer before forming the recess.